Drug resistance in bacteria isolated from patients presenting with wounds at a non-profit Surgical Center in Phnom Penh, Cambodia from 2011-2013

Abstract

Background: Emerging antibiotic resistance amongst clinically significant bacteria is a public health issue of increasing significance worldwide, but it is relatively uncharacterized in Cambodia. In this study we performed standard bacterial cultures on samples from wounds at a Non-Governmental-Organization (NGO) Hospital in Phnom Penh, Cambodia. Testing was performed to elucidate pathogenic bacteria causing wound infections and the antibiotic resistance profiles of bacterial isolates. All testing was performed at the Naval Medical Research Unit, No.2 (NAMRU-2) main laboratory in Phnom Penh, Cambodia.

Methods: Between 2011-2013, a total of 251 specimens were collected from patients at the NGO hospital and analyzed for bacterial infection by standard bacterial cultures techniques. Specimens were all from wounds and anonymous. No specific clinical information accompanied the submitted specimens. Antibiotic susceptibility testing, and phenotypic testing for extended-spectrum beta-lactamase (ESBL) were performed and reported based on CLSI guidelines. Further genetic testing for CTX-M, TEM and SHV ESBLs was accomplished using PCR.

Results: One-hundred and seventy-six specimens were positive following bacterial culture (70 %). Staphlycoccus aureus was the most frequently isolated bacteria. Antibiotic drug resistance testing revealed that 52.5 % of Staphlycoccus aureus isolates were oxacillin resistant. For Escherichia coli isolates, 63.9 % were ciprofloxacin and levofloxacin resistant and 96 % were ESBL producers. Resistance to meropenem and imipenem was observed in one of three Acinetobacter spp isolates.

Conclusions: This study is the first of its kind detailing the antibiotic resistance profiles of pathogenic bacteria causing wound infections at a single surgical hospital in Cambodia. The reported findings of this study demonstrate significant antibiotic resistance in bacteria from injured patients and should serve to guide treatment modalities in Cambodia.

Keywords: Bacteria; Cambodia; Microbial drug resistance; Wound infections.

Fig. 1

Primers used for ESBL PCR testing; Primer names followed by the primer base pair sequences reported in 5’ to 3’ direction for each target ESBL gene, and the resulting product size in base pairs (bp)

Fig. 2

S. aureus and CNSS resistance to oxacillin; Relative percentages of Coagulase-negative Staphylococcus spp. (CNSS) and S. aureus isolates that were sensitive, intermediate, and resistant to oxacillin

Fig. 3

E. coli/E. cloacae/P. mirabilis/K. pneumoniae group antibiotic resistance; The relative percentages of these four Enterobacteriaceae that were sensitive, intermediate, and resistant to commonly used antibiotics with variable degrees of activity against gram negative bacteria

Fig. 4

P. aeruginosa antibiotic resistance; The relative percentages of P. aeruginosa isolates that were sensitive, intermediate, and resistant to common antibiotics with variable degrees of anti-pseudomonas activity

Fig. 5

ESBL testing – PCDD and PCR results; E. coli, K. oxytoca, K. pneumoniae, and P. mirabilis isolates tested for presence of ESBLs by PCDD and PCR. N is the number of isolates tested by PCDD and PCR with the percentage positive in parentheses. The ESBL genes detected by PCR are listed for each species of bacteria tested with the number detected for each gene listed in parentheses